Printing apparatus with a plurality of nozzle heads and method for aligning a plurality of nozzle tips

ABSTRACT

The present disclosure relates to a printing apparatus with a plurality of nozzle heads and method for aligning a plurality of nozzle tips. The printing apparatus with a plurality of nozzle heads according to the present disclosure includes a first nozzle head having a first nozzle tip for discharging ink and a first moving part for moving the first nozzle tip, and disposed at one side of a working area on a substrate; a second nozzle head having a second nozzle tip for discharging ink and a second moving part for moving the second nozzle tip, and disposed at the other side of the working area on the substrate; and a first camera disposed above the substrate to observe the first nozzle tip and the second nozzle tip at the same time.

1. FIELD

The present disclosure relates to a printing apparatus with a pluralityof nozzle heads and method for aligning a plurality of nozzle tips, andmore particularly, to a printing apparatus with a plurality of nozzleheads, having a structure where each of the plurality of nozzle headsare independently controlled, thereby improving the printing speed andproductivity, and where the plurality of nozzles are configured to sharea camera, thereby forming a compact configuration.

2. BACKGROUND

In general, an ink jet device for jetting fluid in the form of dropletshas been mainly applied to inkjet printers in the past, but recently itis being widely applied in high-tech industries such as displaymanufacturing processes, printed circuit board manufacturing processes,and DNA chip manufacturing processes, etc.

The ink jet device is a device for discharging droplets from ink in afluid state, and such ink jet devices are largely divided into thermaltype ink jet devices and piezoelectric type ink jet devices depending onthe method of discharging the droplets. However, recently, forultra-fine printing, electrostatic jet printers that use theelectrodynamic method are widely being used.

An electrostatic jet printer jets ink using the electrostatic forcecaused by a potential difference generated when a voltage is appliedbetween a nozzle and a substrate. Since the electrostatic jet printerdischarges droplets or continuous jets using the force of pulling aliquid surface with the electrostatic force, it is known to havenumerous advantages, for example, unlike other conventional method jetprinters, it enables nano-scale patterning, it can also dischargehigh-viscosity ink, and it can generate droplets uniformly.

However, there is a problem in the printing device according to priorart in that it performs the printing process using a single nozzle,which reduces the productivity.

If a plurality of independently driven nozzles are arranged in parallelin order to improve this problem, productivity can be improved, butthen, there occurs a problem that not only the manufacturing cost of thedevice will excessively increase but also the volume of the device willincrease.

PRIOR ART LITERATURE Patent Literature

-   (PATENT LITERATURE 0001) KOREAN LAID-OPEN PATENT NO. 10-2017-0072748

SUMMARY

Therefore, a purpose of the present disclosure is to resolve theproblems of prior art, that is, to provide a printing apparatus with aplurality of nozzle heads, having a structure where each of theplurality of nozzle heads are independently controlled, therebyimproving the printing speed and productivity, and where the pluralityof nozzles are configured to share a camera, thereby forming a compactconfiguration.

Further, another purpose of the present disclosure is to provide amethod for arranging a plurality of nozzle tips, where the shared cameracan be used to set a reference position for the plurality of nozzle tipsto align the positions, thereby precisely controlling the positions ofthe plurality of nozzle tips that are driven independently.

The aforementioned purpose is achieved by a printing apparatus with aplurality of nozzle heads, the apparatus including a first nozzle headhaving a first nozzle tip for discharging ink and a first moving partfor moving the first nozzle tip, and disposed at one side of a workingarea on a substrate; a second nozzle head having a second nozzle tip fordischarging ink and a second moving part for moving the second nozzletip, and disposed at the other side of the working area on thesubstrate; and a first camera disposed above the substrate to observeboth the first nozzle tip and the second nozzle tip.

Here, it is desirable that the printing apparatus further includes asecond camera disposed to observe both the first nozzle tip and thesecond nozzle tip in an inclined direction.

Further, it is desirable that the printing apparatus further includes acontroller that controls driving of the first moving part and the secondmoving part based on an image obtained in the first camera and thesecond camera, to control each position of the first nozzle tip and thesecond nozzle tip.

Further, it is desirable that the first nozzle head and the secondnozzle head each includes a high voltage application part for applying avoltage to ink in order to discharge the ink in an electrohydrodynamicmethod.

Further, it is desirable that the first nozzle head and the secondnozzle head are disposed to be spaced apart in a first axis directionwith respect to the working area, and the second camera is disposed tobe spaced apart from the first camera in a second axis directionintersecting the first axis.

Further, it is desirable that the first nozzle tip and the second nozzletip are disposed to be inclined so as to have an inclination withrespect to the first axis.

Further, it is desirable that the second camera is disposed to beinclined so as to have an inclination with respect to the second axis.

Further, it is desirable that the first moving part and the secondmoving part are configured to enable at least three axis movements.

Another purpose of the present disclosure is achieved by a method foraligning a plurality of nozzle tips, the method including a first nozzlealigning step of setting a reference position of a first nozzle tip fordischarging ink within a working area through an image of a first cameraobserving the working area above a substrate and a second cameraobserving the working area in an inclined direction; a second nozzlealigning step of setting a reference position of a second nozzle tip fordischarging ink within the working area through the image of the firstcamera and the second camera; a step of detecting a position of asubstrate based on the image of the second camera; and a printingpreparation step of positioning the first nozzle tip and the secondnozzle tip to a printing position on the substrate.

Here, it is desirable that the reference position is set by positioninga distal end of the first nozzle tip or a distal end of the secondnozzle tip at a center of a Field of View (FOV) of the first camera, andthen by positioning the distal end of the first nozzle tip or the distalend of the second nozzle tip at a center of a FOV of the second camera.

Further, it is desirable that after the first nozzle aligning step andthe second nozzle aligning step, a step of moving the first nozzle tipand the second nozzle tip to designated positions is performed, whereineach designated position is spaced apart by a certain distance from thereference position.

Further, it is desirable that the designated positions are set such thatthe first nozzle tip and the second nozzle tip are spaced apart fromeach other in a horizontal direction with respect to the referenceposition so as to prevent interference of the first nozzle tip and thesecond nozzle tip.

Further, it is desirable that a third axis direction position of thedesignated position may be set as a position spaced apart by apredesignated distance from a position of the substrate detected byautofocusing the substrate.

Further, it is desirable that at the step of moving to the designatedposition, the third axis direction position of the first nozzle tip andthe second nozzle tip are adjusted by a driving part that moves thefirst nozzle tip, the second nozzle tip, the first camera and the secondcamera at the same time.

Further, it is desirable that at the printing preparation step, thethird axis direction position of the first nozzle tip and the secondnozzle tip are adjusted by the driving part that moves the first nozzletip, the second nozzle tip, the first camera and the second camera atthe same time.

Further, it is desirable that the step of detecting the position of thesubstrate detects a height of the substrate using an image of the nozzletip included in the image obtained through the second camera and themirroring image of the nozzle tip reflected on the substrate.

According to the present disclosure, there is provided a printingapparatus with a plurality of nozzle heads, having a structure whereeach of the plurality of nozzle heads are independently controlled,thereby improving the printing speed and productivity, and where theplurality of nozzles share a camera, thereby forming a compactconfiguration.

Further, there is provided a method for aligning a plurality of nozzletips, where the shared camera can be used to set a reference positionfor the plurality of nozzle tips to align the positions, therebyprecisely controlling the positions of the plurality of nozzle tips thatare driven independently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a printing apparatus with a plurality ofnozzle heads of the present disclosure;

FIG. 2 is a front view of the printing apparatus with a plurality ofnozzle heads of the present disclosure;

FIG. 3 is a side view of the printing apparatus with a plurality ofnozzle heads of the present disclosure;

FIG. 4 is an image of a first camera image;

FIG. 5 is an image of a second camera image;

FIG. 6 is view of a first nozzle aligning step process;

FIG. 7 is a view of the second camera image;

FIG. 8 is a view of the first camera image;

FIG. 9 is a view of a step of moving a first nozzle tip to a designatedposition after the first nozzle aligning step;

FIG. 10 is a view of a second nozzle aligning step process;

FIG. 11 is a view of a step of moving a second nozzle tip to adesignated position after the second nozzle aligning step;

FIG. 12 is a view of a step of detecting a position of a substrate basedon the second camera image; and

FIG. 13 is a view of a printing preparation step.

DETAILED DESCRIPTION

Prior to the description, it is to be noted that in numerousembodiments, components having the same configurations will be typicallydescribed in the first embodiment using the same reference numerals, andin rest of the embodiments, only the configurations different from thefirst embodiment will be described.

Hereinbelow, referring to the attached drawings, a printing apparatuswith a plurality of nozzle heads according to one embodiment of thepresent disclosure will be described in detail.

Of the attached drawings, FIG. 1 is a perspective view of a printingapparatus with a plurality of nozzle heads of the present disclosure,FIG. 2 is a front view of the printing apparatus with a plurality ofnozzle heads of the present disclosure, FIG. 3 is a side view of theprinting apparatus with a plurality of nozzle heads of the presentdisclosure, FIG. 4 is an image of a first camera image, and FIG. 5 is animage of a second camera image.

The printing apparatus with a plurality of nozzle heads of the presentdisclosure illustrated in the abovementioned drawings includes a firstnozzle head 110, a second nozzle head 120, a first camera 130, a secondcamera 140 and a controller.

First, in the present embodiment, description is made with reference toan electrostatic jet printer that uses an electrohydrodynamic method forultra-fine printing, but there is no limitation thereto, and thus thetechnical idea of the present disclosure may be applied to other typesof printers that jet ink using nozzles as well. Further, in the presentembodiment, a first axis is described as x axis, a second axis isdescribed as y axis, and a third axis is described as z axis, but thereis no limitation thereto.

The first nozzle head 110 includes a first nozzle tip for dischargingink onto a substrate at one section of a working area, a first movingpart 112 for moving the first nozzle tip 111, and a first high voltageapplication part 113 for applying a high voltage to an electrode formedinside the first nozzle tip 111 in order to discharge ink in anelectrohydrodynamic method.

The first nozzle tip 111 has inside thereof a chamber for accommodatingink, and discharges ink towards the substrate. Such a first nozzle tip111 is disposed with an inclination with respect to a first axis so asto be observed in real time by means of the first camera 130 whichphotographs an image downwardly from above at the working area and thesecond camera 140 which is arranged near the working area andphotographs an image in a downwardly inclined direction from above.Meanwhile, in the drawings of the present embodiment, the first nozzletip 111 is illustrated as a cartridge type that is capable of beingattached and detached so as to be replaced, but there is no limitationthereto.

The first moving part 112 is configured to be able to perform three-axismovements between the first nozzle tip 111 and a base, and the firstmoving part 112 may be configured to include a first axis linear drivemechanism, a second axis linear drive mechanism and a third axis lineardrive mechanism. Such a configuration of the first moving part 112 is awell-known technology, and thus specific description thereof will beomitted. Meanwhile, in the present embodiment, it is described that thefirst moving part 112 has three degrees of freedom, but there is nolimitation thereto. Modifications can be made in various forms whendeemed necessary such as configuring the first moving part 112 to havesix degrees of freedom for movements such as yaw, pitch, roll and thelike.

The first nozzle tip 111 may be formed of a nozzle made of a conductiveor non-conductive material of a capillary type widely used inelectrostatic jet printers, and an outer diameter of the nozzle tip maybe 1 to 300 μm, and an inner diameter of the nozzle tip may be 0.5 to250 μm, and such an outer diameter and inner diameter of the nozzle tipmay be changed according to needs such as the physical properties of theink or the printing environment, etc. When the first high voltageapplication part 113 applies a high voltage to the electrode provided atthe first nozzle tip 111 side, an electric field is formed between theelectrode and the substrate. Here, polarities of the electrode and thesubstrate may be opposite to each other, or the substrate may begrounded. Due to the high voltage applied to the electrode, the electricfield is formed in a direction from the electrode towards the substrate,and using the electrostatic force caused by the electric field, ink canbe finely discharged. This printing principle of an electrostatic jetprinter is a well-known technology, and thus detailed descriptionthereof will be omitted.

The second nozzle head 120 includes a second nozzle tip 121 fordischarging ink at the other section of the working area onto thesubstrate, a second moving part 122 for moving the second nozzle tip 121and a second high voltage application part 123 for applying a highvoltage to an electrode formed inside the second nozzle tip 121 in orderto discharge ink in an electrohydrodynamic method.

The second nozzle tip 121, the second moving part 122 and the secondhigh voltage application part 123 constituting such a second nozzle head120 are made in the same form as the first nozzle tip 111, the firstmoving part 112 and the first high voltage application part 113 of thefirst nozzle head 110, and thus detailed description thereof will beomitted.

The first nozzle head 110 and the second nozzle head 120 are disposed tobe spaced apart from each other in the first axis direction, and aredisposed in a form symmetrical to the first nozzle head 110 with respectto the working area.

The first camera 130 is disposed above the substrate to photograph theworking area in a vertically downward direction from above. Whenphotographing the working area in an inclined direction, distortion ofimage may occur. However, by photographing the working area at avertical location above the substrate, the process of the ink beingadhered and the shape of the pattern being formed on the substrate bythe adhesion of the ink can be obtained as images without distortion.

The second camera 140 is disposed near the working area to photographthe working area in an inclined direction from above. That is, thesecond camera 140 is disposed to be spaced apart from the first camera130 in a second axis direction intersecting the first axis, and isdisposed with an inclination with respect to the second axis. When thesecond camera 140 is disposed with an inclination as described above,through an image of the second camera 140, it is possible to see animage of the first nozzle tip 111 and an image of the second nozzle tip121, and a mirroring image of the first nozzle tip 111 and a mirroringimage of the second nozzle tip 121 reflected on the substrate at thesame time.

The Field of View (FOV) of the first camera 130 and the second camera140 are set to observe the first nozzle tip 111 and the second nozzletip 121 within the working area at the same time. Here, the Field ofView (FOV) refers to the size of a photographed image, that is, therange of an object that can be viewed by the camera when the cameraphotographed the object. For example, the FOV of the first camera 130may be set to 425×454 μm while the FOV of the second camera 140 is setto 800×600 μm that is relatively greater than the FOV of the firstcamera 130. Accordingly, by focusing the image of the first nozzle tip111 and the second nozzle tip 121 through the image of the first camera130 in a state in which the position of the first nozzle tip 111 and thesecond nozzle tip 121 are recognized through the image of the secondcamera 140, it is possible to set the reference position P1 of the firstnozzle tip 111 and the second nozzle 121.

Further, a Depth of Field (DOF) of the first camera 140 may be set to benot more than ±1.6 μm in order to set the reference position P1 of thefirst nozzle tip 111 and the second nozzle tip 121 precisely, and such adepth of the DOF area may be appropriately changed depending on thecharacteristics of the lens applied to the first camera 140. At the bestfocus position within the DOF area of the first camera 140 describedabove, the reference position P1 of the first nozzle tip 111 and thesecond nozzle tip 121 may be set. That is, once the first nozzle tip 111and the second nozzle tip 121 are out of the DOF area of the firstcamera 130, since the image is blurred and the image contrast decreases,visualization and detection of the first nozzle tip 111 and the secondnozzle tip 121 within the image of the first camera 130 becomesimpossible. Accordingly, it is possible to find the best focus point byadjusting the position of the first nozzle tip 111 and the second nozzletip 121 to the submicron level within the DOF area of the first camera130, and set this best focus point as the reference position P1 of thefirst nozzle tip 111 and the second nozzle tip 121.

Further, the pixel resolution of the first camera 130 may be set to0.1725 μm/pixel, and the pixel resolution of the second camera 140 maybe set to 0.625 μm/pixel. That is, since the magnification of the firstcamera 130 is set to be higher than the second camera 140, the pixelresolution of the first camera 130 may be set to be relatively lowerthan the second camera 140.

The controller is configured to control the driving of the first movingpart 112 and the second moving part 122 based on the image obtained inthe first camera 130 and the second camera 140, and control each of theposition of the first nozzle tip 111 and the position of the secondnozzle tip 121. That is, the controller may receive the image obtainedthrough the first camera 130 and the second camera 140, analyze theimage of the first nozzle tip 111 and the second nozzle tip 121displayed on the screen, and then provide the first moving part 112 andthe second moving part 122 with driving signals for movement of thefirst nozzle tip 111 and the second nozzle tip 121.

Meanwhile, the first nozzle head 110, the second nozzle head 120, thefirst camera 130 and the second camera 140 may be installed on a support150, and the support 150 may be configured to move in a third axisdirection by a separate driving part (not illustrated). The printingapparatus with a plurality of nozzle heads of the present disclosureconfigured as described above can form a pattern on the substrate whilesimultaneously observing, through the image of the first camera 130 andthe second camera 140, the first nozzle tip 111 and the second nozzletip 121 that may each move independently, thereby improving the printingspeed and productivity, and a compact configuration can be made byhaving the plurality of nozzles share a camera.

Next, a method for aligning a plurality of nozzle tips of the presentdisclosure will be described.

Of the attached drawings, FIG. 6 is view of a first nozzle aligning stepprocess, FIG. 7 is a view of the second camera image, FIG. 8 is a viewof the first camera image, FIG. 9 is a view of a step of moving a firstnozzle tip to a designated position after the first nozzle aligningstep, FIG. 10 is a view of a second nozzle aligning step process, FIG.11 is a view of a step of moving a second nozzle tip to a designatedposition after the second nozzle aligning step, FIG. 12 is a view of astep of detecting a position of a substrate based on the second cameraimage, and FIG. 13 is a view of a printing preparation step.

The method for aligning a plurality of nozzle tips of the presentdisclosure includes a first nozzle aligning step (S110), a first nozzlemoving step (S120), a second nozzle aligning step (S130), a secondnozzle moving step (S140), a step of detecting a substrate position(S150) and a step of preparing printing (S160).

First, as illustrated in FIGS. 6 to 8 , the first nozzle aligning step(S110) includes setting a reference position P1 (origin point inrelative coordinates) of the first nozzle tip 111 for discharging inkwithin the working area using the first camera 130 that observes theworking area from the above in a third axis Z direction of the workingarea and the second camera 140 that observes the working area from theabove in a second axis Y direction of the working area.

First, as in FIG. 7 , a first axis direction X, a second axis directionY and a third axis direction Z position of the first nozzle tip 111 areadjusted such that a distal end of the first nozzle tip 111 ispositioned at a center of the FOV of an image C2 of the second camera140. Specifically, the position of the first nozzle tip 111 is adjustedsuch that the distal end of the first nozzle tip 111 is positioned atthe center of the FOV of the image C2 of the second camera 140, and thenthe position of the first nozzle tip 111 is adjusted such that thedistal end of the first nozzle tip 111 moves to the best focus positionthat is most clearly visible within the DOF area of the second camera140.

Next, as in FIG. 8 , the first axis direction X, the second axisdirection Y and the third axis direction Z position of the first nozzletip 111 are adjusted such that the distal end of the first nozzle tip111 is positioned at a center of the FOV of the image C1 of the firstcamera 130, and as shown in FIG. 6 , the position of the first nozzletip 111 is adjusted such that the distal end of the first nozzle tip 111moves to the best focus position that is most clearly visible within theDOF area of the first camera 130, and then the corresponding positionsare set as the reference position P1 (relative coordinates origin point)of the first nozzle tip 111.

That is, by adjusting the first axis direction X, the second axisdirection Y, and the third axis direction Z position of the first nozzletip 111 to the center of the FOV of the image C2 and the best focusposition of the second camera 140, and then adjusting the first axisdirection X, the second axis direction Y, and the third axis direction Zposition of the first nozzle tip 111 to the best focus position and thecenter of FOV in the image C2 of the first camera 130 that has a highermagnification compared to the second camera 140, it is possible toimprove the precision of setting of the reference position P1.

Not only that, since the reference position P1 of the first nozzle tip111 and the reference position of the second nozzle tip 121 are setrespectively through the first camera 130 and the second camera 140having fixed positions, the reference position P1 of the first nozzletip 111 and the reference position P1 of the second nozzle tip 121 maybe set as the same point.

Here, since the first camera 130 is in a fixed state where changing theposture is not possible, it is desirable to perform a process ofaligning the center of the FOV of the image C2 of the second camera tothe center of the image C1 of the first camera prior to setting thereference position P1.

As illustrated in FIG. 9 , at the first nozzle moving step (S120), aposition spaced apart by a certain distance in the first axis Xdirection from the reference position P1 set for the first nozzle tip111 is set as the designated position P2, and then, in order to performthe second nozzle aligning step (S130), the first nozzle tip 111 ismoved to a certain position far from the reference position P1.

As illustrated in FIG. 10 , at second nozzle aligning step (S130), thefirst axis direction X position and the second axis direction Y positionof the second nozzle tip 121 are adjusted such that the distal end ofthe second nozzle tip 121 is positioned at each of the center of theimage C2 of the second camera 140 and the image C1 of the first camera130, and then the third axis Z direction position of the second nozzletip 121 is adjusted such that the distal end of the second nozzle tip121 moves to the best focus position of the image C1 of the first camera130, thereby setting the reference position P1 (relative coordinatesorigin point) of the second nozzle tip 121. This second nozzle aligningstep (S130) consists of the same process as the first nozzle aligningstep (S110), and thus detailed description is omitted.

Next, as illustrated in FIG. 11 , at the second nozzle moving step(S140), a location spaced apart from the reference position P1 for thesecond nozzle tip 121 in the first axis X direction is set as thedesignated position P2. It is desirable that in order to preventinterference of the first nozzle tip 111 and the second nozzle tip 121,the designated positions P2 are set to positions that are mutuallyspaced apart from the reference position P1 in the first axis Xdirection. After the designated position P2 of the second nozzle tip 121is set, the second nozzle tip 121 may be moved to a certain position faraway from the reference position P1 in order to position the substrate Son a stage.

Meanwhile, after seating the substrate S on the stage, the first nozzletip 111 and the second nozzle tip 121 are moved to each of thedesignated positions P2, respectively.

Here, it desirable that the third axis Z direction position of thedesignated position P2 is set to be spaced apart from the substrate S inthe third axis Z direction and at the same time the first nozzle tip andthe second nozzle tip are positioned within the FOV of the image of thesecond camera such that the first nozzle tip 111 and the second nozzletip 121 do not collide with the substrate S, and the third axis Zdirection position of the first nozzle tip 111 and the second nozzle tip121 are adjusted by the driving part that moves the support 150.

In the present embodiment, the first camera 130 can be used to autofocusthe substrate S and identify the third axis Z direction position of thesubstrate S, and then the third axis Z direction position of the firstnozzle tip 111 and the second nozzle tip 121 may be selected such thatthey are spaced apart from the substrate S by a predesignated distance.

Meanwhile, in the present embodiment, using the first camera 130 toautofocus the substrate S and detect the third axis direction positionof the substrate S has been described as an example, but there is nolimitation thereto, and thus it will also be possible to provide aseparate autofocusing equipment that is based on laser or white LED forthe autofocusing of the substrate S.

As illustrated in FIG. 12 , at the step of detecting the position of thesubstrate (S150), it is possible to precisely detect the third axis Zdirection position of the substrate S based on the image of the secondcamera 140.

Specifically, since the second camera 140 is installed to observe theworking area from above at one side of the working area in a downwardinclined direction, the image of the second camera 140 will show theimages of the first nozzle tip 111 and the second nozzle tip 121together with the mirroring images of the first nozzle tip 111 and thesecond nozzle tip 121 reflected on the substrate S.

Accordingly, the farther away the first nozzle tip 111 and the secondnozzle tip 121 are from the substrate S, the greater the distancebetween the nozzle tip image and the mirroring image, and the closer thefirst nozzle tip 111 and the second nozzle tip 121 are from thesubstrate S, the closer the distance between the nozzle tip image andthe mirroring image, and thus it is possible to analyze the image of thesecond camera 140 and detect the third axis Z direction position of thesubstrate S based on the designated position P2 of the first nozzle tip111 and the second nozzle tip 121.

Thereafter, as illustrated in FIG. 13 , at the printing preparation step(S160), using the driving part that moves the support 150, the firstnozzle tip 111 and the second nozzle tip 121 may be positioned to aprinting position on the substrate S, and then, by controlling theposition of the first nozzle tip 111 and the second nozzle tip 121according to a designated circuit pattern shape, the designated circuitpattern shape may be printed on the substrate S.

The scope of right of the present disclosure is not limited to theabove-described embodiments, but may be implemented in various forms ofembodiments within the scope of the appended claims set. Withoutdeparting from the gist of the present disclosure claimed in the claimsset, it is considered to be within the scope of the claims of thepresent disclosure to various extents that can be modified by any personskilled in the art to which the invention pertains.

REFERENCE NUMERALS

-   110: FIRST NOZZLE HEAD, 111: FIRST NOZZLE TIP, 112: FIRST MOVING    PART, 113: FIRST HIGH VOLTAGE APPLICATION PART, 120: SECOND NOZZLE    HEAD, 121: SECOND NOZZLE TIP, 122: SECOND MOVING PART, 123: SECOND    HIGH VOLTAGE APPLICATION PART, 130: FIRST CAMERA, 140: SECOND    CAMERA, 150: SUPPORT, S: SUBSTRATE, P1: REFERENCE POSITION, P2:    DESIGNATED POSITION

What is claimed is:
 1. A printing apparatus with a plurality of nozzleheads, the apparatus comprising: a first nozzle head having a firstnozzle tip for discharging ink and a first moving part for moving thefirst nozzle tip, and disposed at one section of a working area on asubstrate; a second nozzle head having a second nozzle tip fordischarging ink and a second moving part for moving the second nozzletip, and disposed at the other section of the working area on thesubstrate; and a first camera disposed above the substrate to observeboth the first nozzle tip and the second nozzle tip.
 2. The printingapparatus with a plurality of nozzle heads, according to claim 1,further comprising a second camera disposed to observe both the firstnozzle tip and the second nozzle tip in an inclined direction.
 3. Theprinting apparatus with a plurality of nozzle heads, according to claim2, further comprising a controller that controls driving of the firstmoving part and the second moving part based on an image obtained in thefirst camera and the second camera, to control each position of thefirst nozzle tip and the second nozzle tip.
 4. The printing apparatuswith a plurality of nozzle heads, according to claim 1, wherein thefirst nozzle head and the second nozzle head each comprises a highvoltage application part for applying a voltage to ink in order todischarge the ink in an electrohydrodynamic method.
 5. The printingapparatus with a plurality of nozzle heads, according to claim 2,wherein the first nozzle head and the second nozzle head are disposed tobe spaced apart in a first axis direction with respect to the workingarea, and the second camera is disposed to be spaced apart from thefirst camera in a second axis direction intersecting the first axis. 6.The printing apparatus with a plurality of nozzle heads, according toclaim 5, wherein the first nozzle tip and the second nozzle tip aredisposed to be inclined so as to have an inclination with respect to thefirst axis.
 7. The printing apparatus with a plurality of nozzle heads,according to claim 5, wherein the second camera is disposed to beinclined so as to have an inclination with respect to the second axis.8. The printing apparatus with a plurality of nozzle heads, according toclaim 5, wherein the first moving part and the second moving part areconfigured to enable at least three axis movements.
 9. A method foraligning a plurality of nozzle tips, the method comprising: a firstnozzle aligning step of setting a reference position of a first nozzletip for discharging ink within a working area through an image of afirst camera observing the working area above a substrate and a secondcamera observing the working area in an inclined direction; a secondnozzle aligning step of setting a reference position of a second nozzletip for discharging ink within the working area through the image of thefirst camera and the second camera; a step of detecting a position of asubstrate based on the image of the second camera; and a printingpreparation step of positioning the first nozzle tip and the secondnozzle tip to a printing position on the substrate.
 10. The method foraligning a plurality of nozzle tips, according to claim 9, wherein thereference position is set by positioning a distal end of the firstnozzle tip or a distal end of the second nozzle tip at a center of aField of View (FOV) of the first camera, and then by positioning thedistal end of the first nozzle tip or the distal end of the secondnozzle tip at a center of a FOV of the second camera.
 11. The method foraligning a plurality of nozzle tips, according to claim 9, wherein afterthe first nozzle aligning step and the second nozzle aligning step, astep of moving the first nozzle tip and the second nozzle tip todesignated positions is performed, wherein each designated position isspaced apart by a certain distance from the reference position.
 12. Themethod for aligning a plurality of nozzle tips, according to claim 11,wherein the designated positions are set such that the first nozzle tipand the second nozzle tip are spaced apart from each other in ahorizontal direction with respect to the reference position so as toprevent interference of the first nozzle tip and the second nozzle tip.13. The method for aligning a plurality of nozzle tips, according toclaim 12, wherein a third axis direction position of the designatedposition may be set as a position spaced apart by a predesignateddistance from a position of the substrate detected by autofocusing thesubstrate.
 14. The method for aligning a plurality of nozzle tips,according to claim 13, wherein at the step of moving to the designatedposition, the third axis direction position of the first nozzle tip andthe second nozzle tip are adjusted by a driving part that moves thefirst nozzle tip, the second nozzle tip, the first camera and the secondcamera at the same time.
 15. The method for aligning a plurality ofnozzle tips, according to claim 14, wherein at the printing preparationstep, the third axis direction position of the first nozzle tip and thesecond nozzle tip are adjusted by the driving part that moves the firstnozzle tip, the second nozzle tip, the first camera and the secondcamera at the same time.
 16. The method for aligning a plurality ofnozzle tips, according to claim 9, wherein the step of detecting theposition of the substrate comprising: detecting a height of thesubstrate using an image of the nozzle tip included in the imageobtained through the second camera and the mirroring image of the nozzletip reflected on the substrate.